> Hashes have no problem with combining marks.

Thanks for the confirmation, I thought that was how I understood the documentation, but I wasn't sure.

> The problem is probably that the character appears both in composed and decomposed form.

If they do, I don't understand where it comes from. I entered them both in composed form. Note the two "a"-like things are different, but you only see it if you use a font that makes a difference between "small alpha" and "a".

> You can use Unicode::Normalize's NFC or NFD to normalize the form.

Thanks. I read up on normalization and tried replacing 
 
my $key = $1;

[download]
with 
 
my $key = NFD($1); # or NFC, or even NFKD/NFKC

[download]
as well as replacing the last for-loop with 
foreach my $letter (@letters) {
    my $norm_letter = NFD($letter); 
    my @features = @{ $hash{$norm_letter} };
    print join " ", @features;
    print "\n";
}

[download]

It still doesn't work though. The error message complains about not finding $nfd_letter in the hash, although the for-loop I commented out in the original script definitely shows it was added:
Can't use an undefined value as an ARRAY reference at ./test.plx line 31, <INPUTFILE> line 2.

The script is thus now (including the changes suggested by Jim, too):

use Unicode::Normalize;

binmode(STDOUT, ':encoding(UTF-8)');

open HASH, '<:encoding(UTF-8)', 'test_hash.txt';
my %hash = ();
while (my $line=<HASH>) {
    chomp $line;
    $line =~ s/^(.*?)\t//;
    my $key = NFD($1); 
    my @line = split /\s+/, $line;
    $hash{$key} = \@line;
}
# foreach my $phoneme (keys %hash) {
#     print $phoneme . ":";
#     my @line = @{ $hash{$phoneme} };
#     print join ",", @line;
#     print "\n";
# }

open INPUTFILE, '<:encoding(UTF-8)', 'test_input.txt';
while (my $entry = <INPUTFILE>) {
    chomp $entry;
    print $entry . "\n";

    my @letters = $entry =~ /(\X)/g;

    foreach my $letter (@letters) {
        my $norm_letter = NFD($letter); 
        my @features = @{ $hash{$norm_letter} };
        print join " ", @features;
        print "\n";
    }
}

[download]

In reply to Re^2: Unicode combining characters as hash keys? by Anonymous Monk
in thread Unicode combining characters as hash keys? by Anonymous Monk

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